1) Field of the Invention
The present invention relates to a spectral imaging apparatus provided with a spectral transmittance variable element and a method of adjusting a spectral transmittance variable element in a spectral imaging apparatus.
2) Description of Related Art
Conventionally, there have been used, in the fields such as image observation and optical communication, spectral transmittance variable elements that have spectral transmittance characteristics such that the transmittance is variable with wavelength, are capable of changing the period of variation, and convert entering or reflecting light into light having a plurality of peak wavelengths.
As apparatuses using such spectral transmittance variable elements, for instance, there are known an optical communication system disclosed in JP Kokai No. Hei 09-186673 and an image observation apparatus disclosed in JP Kokai No. 2005-308688.
In the optical communication system disclosed in JP Kokai No. Hei 09-186673 and the image observation apparatus disclosed in JP Kokai No. 2005-308688, Fabry-Pérot etalons are used as spectral transmittance variable elements. The Fabry-pérot etalons make use of interference of light, and are capable of changing wavelengths of light which they can transmit or reflect by changing a distance between a pair of mirror surfaces arranged to face each other. Such mirror surfaces of a Fabry-Pérot etalon usually are formed by application of coating on optical substrates such as quartz.
In the optical communication system disclosed in JP Kokai No. Hei 09-86673, the configuration is made so that calibration is performed in a path of light for calibration provided independent of a path of light for transmission.